Treatment of municipal wastewater using constructed wetland : removal of orthophosphate and ammonia nitrogen

摘要

Municipal wastewater is one of the major concerns of the environment problems. As the wastewater is found to be highly contaminated, it could not be discharged directly into the environment. Therefore, wastewater treatment is essential to minimize the effect of the contaminants to nature. Based on previous studies, constructed wetland system (CWS) was proved to have high efficiency in treating industrial wastewater with low operating and maintenance cost. The industrial wastewater studied was food waste which was taken from UMP’s cafeteria drainage system . In this research, lab scale of free water surface constructed wetlands was designed with the water lettuce (Pistia Stratiotes) as the wetland plant. The parameter studied including ammonia nitrogen (NH3-N) and orthophosphate (Po43-). In order to investigate the effectiveness of the systems, three variables were studied which were the number of cycle (1 and 2), the wastewater concentration (dilute and non-dilute) and the physical appearance of the plants during the treatment. The results showed that NH3-N was removed at high removal efficiency meanwhile Po43-removal appeared at low removal efficiency. Both NH3-N and Po43- removal showed better results in the CWS with 2 cycles. In term of the different municipal wastewater concentration variable, the CWS with non-dilute sample showed the highest removal efficiency for NH3-N and municipal wastewater concentration with dilute sample (DF=20) showed the highest removal efficiency for Po43-. For plant growth observation, at the end of the treatment, many of the water lettuces were wilted. As conclusion, this study showed that constructed wetland can remove contaminant in cafeteria wastewater.